1. Field of the Invention
This invention relates to the production of multiple glazings with seals of organic material and more particularly pumping and distribution of these organic materials to provide a continuous bead intended to serve as a seal and insert between two consecutive glass sheets of a multiple glazing.
2. Discussion of the Background Art
It is known from French patent application FR-A-No. 2294313 to produce a continuous bead of material of the butyl rubber type and to deposit it on a glass sheet during formation of a multiple glazing after adding a second glass sheet. To make this bead, a screw extruder is fed with slabs of organic material each about 7 kg, one slab being used while the other one is being preheated to be used next. Consequently there is a need for the constant presence of a person responsible for feeding the screw extruder with new slabs.
Moreover, the extruder is a heavy and quite powerful machine, and consequently rather expensive, because of the high performance that is required for correct extrusion, which requires a stop of the extrusion at each corner of the glazing and a restarting each time with an immediately constant output.
Further, it is known from European patent application EP-A No. 171309 to produce this continuous bead by extruding the organic material with a pump dipping directly into a large-capacity drum filled with said material, to subject this material to various operations concurrently to lower its viscosity and to make possible the formation of a uniform continuous bead able, if necessary, to be of great length and/or great height for making large-sized multiple glazings and with an air space of great thickness between the glass sheets. These various operations which make possible the formation of a continuous bead of great length and/or great height use a first pump, then a gear pump, then a variable volume reserve and in general an entire series of devices which make the installation expensive, complex and which complicate control of the temperature of the treated material.
There is generally known from European patent application EP-A-No. 238380 a reciprocating pump dipping into the drum of organic material, associated with a conical heating plate resting on the material contained in the drum, this unit being able to provide a high and continuous delivery of organic material, even a material as viscous and as hard to pump as butyl rubber. But with such a reciprocating pump the problem arises of perfect regularity of the delivery at the moment of change of direction of the pump. Since the space between two consecutive glass sheets of the multiple glazing, or in other words the thickness of the enclosed layer of gas, generally air, depends directly on the thickness and regularity of the thickness of the bead placed between said two glass sheets, and since the insulation performance of the multiple glazing and its aptitude for remaining perfectly transparent without moisture between the glass sheets, depend on the tightness of the seals between the glass sheets and in particular the tightness and regularity of the bead of the butyl rubber type, it is important that there be a perfect quality of the bead forming the seal and insert if well-calibrated glazings having good performance are desired. Further, with thick insert air layers, the delivery provided by the pump can be momentarily insufficient, even when its average delivery is greater than the theoretical necessary delivery rate.